Recapping and retreading mold



April 6, 1943.

A. B. CLEVELAND I RECAPPING AND RETREADING vMOLD Filed April 2,4 1937 2Sheets-Sheet 1 n Bm ATTORNEY,

April 6 1943 l A. B. CLEVELAND 2,315,770

RECAPPING A-ND RETREADING MOLD Filed April 2, 1937 2 Sheets-Sheet 2INVENTOR. Arch B. C/eVe/and Bywm M.

ATTORNEY.

Patented Apr. 6, 1943 UNITED stares Parser Price 2,315,770 REcnPrING ANDRETREADING Moto Arch B. Cleveland, Los Angeles, Calif.

Application April 2, 1937, Serial No. 134,493

(c1. is-is) 6 Claims.

` My invention relates to tire vulcanizing molds, and more particularlyto a vulcanizing mold that may be used either for recapping orretreading a tire.

In the reclaiming or restoring to active life of worn automobile tires,two methods have been employed, one of these methods being known asretreading, the essential features of which are the cutting away of aportion of the worn material on the outer road-contacting face or treadof the tire and also cutting back and roughening of the material of theshoulder strip of the tire (the shoulder strip being dened as thatportion of the rubber material of the tire which extends along the sideof the tire from its junction with the road-contacting face and itsjunction or union with the thin side wall of the tire) and thencompletely covering the tread and the shoulder strip with new rubbermaterial to build the tread and shoulder strip back to a predeterminedthickness and vulcanizing this new material in place.

The other method is known as recapping and is employed in place ofretreading whenever the worn tire is worn only along the tread portionand none of the cords or fabric of the tire has been worn through, orthe rubber along the shoulder strip is not blistered or broken away fromthe cords or fabric of the tire. In such instances the tire merely needsadditional material placed upon the tread portion and not only is itunnecessary but it is undesirable to extend 'the new material along theshoulder strip of the tire since during the curing process theapplication of heat to the undamaged shoulder strip may injure ordestroy a portion of the goed rubber remaining on the shoulder strip.

Heretofore retreading operations have been performed in what is known asa retreading mold, namely, one in which the matrices employed for thecuring of the new tread material extended not only across the treadportion of the tire but a considerable distance down along the shoulderstrip thereof, while recapping operations have been performed in what isknown as a recapping mold, in which the matrices employed extended onlyacross the road-contacting outer face portions of the tire between theopposite shoulders or corners formed by the junction of the shoulderstrip with the road-contacting face or tread and made no substantialcontact along theY shoulder strip ci the tire. It has therefore beennecessary to employ two distinctly diierent types of molds forperforming the two distinct operations.

It is therefore an object of my invention to provide a single machinewhich'may l.be employed for either retreading operations or recappingoperations.

Another obje-ct of my invention is to provide a machine of the characterset forth in the preceding paragraph wherein the same tread matrix maybe employed for either retreading or recapping operations, the recappingmatrix being con-v vertible from a recapping matrix to a retreadingmatrix by the mere insertion in the machine of shoulder strip engagingmatrix rings cooperating with the tread matrix to extend the effectivearea of the matrix along at least a portion of the area of the shoulderstrip of the tire.

Another object of my invention is to provide a machine'of the characterset forth in the preceding paragraph wherein removable shoulder stripringsare associated with a recapping tread matrix in such manner as toconduct heat from the recapping tread m'atrixto desired portions of theside walls of the tire when a retreading operation is indicated. I

Another object of my inventionv is to provide a combined retreading andrecapping` machine of the character set forth in the precedingparagraphs wherein the matrices are adapted to extend continuously aboutthe circumference of the tire in what is known as a full circleretreading, recapping or molding operation, and in which the matricesare carried by a pair of complementary shell membersfseparable along aplane transverse to the axis of the tire and hinged together in suchmanner as will permit both a swinging movement of the members relativeto each other and also a straight line separation between the members.

Another object is to provide hinge means for a tire vulcanizing moldthat will not only articulate. the halves of the mold, but also permitmovement of one half away from the other half apart from -a swingingmovement. L

Still another object is to provide novel means for opening the moldafter the Vulcanizing process is completed, and novel means for removingthe tire from the mold. v

The invention also comprises novel details of construction and novelcombinations and arrangements of parts, which will more fully appear inthe course of the following description.r

In the drawings, like reference characters des'- ignate similar parts inthe several views.

Figure 1 is a plan view of a tire vulcanizing mold embodying features ofmy invention.

Figure 2 is a side elevation looking in the direc tion of thearrow A- ofFigure 1.

Figure 3 is an enlarged section taken on the line 3-3 of Figure 1.

Figure 4 is an enlarged section taken on the line 4-4 of Figure 1, butshowing retread rings, hereinafter described, removed.

Figure 5 is an enlarged section taken on the line 5-5 of Figure 1.

Referring to the drawings, I have illustrated my vulcanizer ascomprising a shell or mold 6 of the typeknown as the full circle mold,that is, the moldcomprisesan annular ring adapted to receive the entireperiphery of a tire and to cure new tread material thereon throughoutthe full: circle described by the tread of the tire in a singleoperation. The shell 5 is-preferably'dis posed upon a horizontal axisand.A formed of a pair of separable complementary halves 9 and' 1, thelower half 1 constituting-fa base*half."which-l may be supported at anydesired height. above a floor by means of a plurality of legs 8'. Theupper.` o1: movable. halft 9J' of; the. mold hingedly to thezlower."half' asiby' means; ot one or more hinges I0, two of whichareiliustrated herein; each of. whichY comprisesarr upper hinge memberitl; andanluwer hinge` member bt pivoted together as shown,4 irr Eig..2,. the: upperf member lili being` rigidly secured'. as: shown. atV t4:in a radiallyext'ending: ear` Ii formed upon the upper memberf Swhi'lethelcwermember |2tof-the= hinge I0 iss vertically slidable; ini airadially extending een Ir3- formed. upon the base half: 1:, thus.adapt;- ing the: upper half- 9: tbe swung: bingedlyaway from the base 1wheneven thezmold tosbe open or toward the base haelty when: the.moldi"sto closed but. permitting considerable latitude of movement ofthe upper halt nr a plaire:parallel-'` to the base halt 1' to permit`the: mold. or: shell', to adust itselli for' the. reception ofi tires-vof different cross sectional diameters, thisivertical; ad-

justment'- of' theY upper half 9"- being' limited by MBEHS'OFTIHIUDUS ITand' |3- in the lowermemsber I2 of the hinge, disposed respective-ly onopposite sides oftheear I6;

The molti".Y or shelll 6i constitutes the housing and mounting for arecapping matrix`J I`9i t'o extenti*y acrossA the roadecont'acting faceof' the tire between` theL shoulders thereof, preferably comprising' apair'off annular'ring members fau: and wb' separated along 'line 211,the -matrixsection I'a being secured to= the baselialfIl lv of theshell' byprovidingf a plurality' of radially extending lugs or bosses'2| onthe matrix' section F921 spaced al'zfoutl the circle described-v bythe matrix section- Ha; eachA of" the bosses A 2|f beingl provided?with: a Boreoi" socket 22 adapted to receive; the end of a'pin 23extending radially through the outer wall? of the' shell half 1" (see-Fig: The" pins 23 are removable but' are; preferably normally` urgedtoward; the sockets 22. by means of' springs 24, one end of whichengages the pin` 23 and the other end. of which. engages the shell halfT'.

The upper:r matrix section 13b' is similarly removably' secured to themoyable half i ofthe mold' so that the matrix section IBD is movedltowardand. away from4 the matrix Lila as the mold; is closed or opened..Each ofthe matrix sections is provided a suitable heating` element.adapted to supplyy heat thereto, theheating elements being. indicated.`herein as steam pipes. 25hy andV 25h embedded. respectively in thematrix. sections Ilia', and wir. Steam may be suppliedy toz. the. matrixsection isb byY means. of. an inlet pipe 26 (see. Fig., L).I andiexhaust` steam removed` therefrom by means of pipe 21; Shnilarly steam.may be;-

supplied to the matrix section 19o through a pipe 28 (see Fig. 2).

In Fig. 4 I have illustrated a tire carcass A which is assumed to haveonly its road-contacting outer face or tread (between the shoulders:r-x) worn smooth, but which has not been worn down through the breakerstrip or any of the layers of cords or fabric of the tire and henceneeds only to have the tread portion of the tire rebuilt thereon and toaccomplish this the cid rubber on. the outer road-contacting surface ofthe tire is roughened up, cement applied thereto and a sufficient numberof layers of new rubber material B are placed thereon to build the treadof the tire back to the desired thickness.

-To. cure thisnew rubber it is necessary to apply heat only to the outerperiphery of the tire and it; is notv desirable to heat the old rubberof the tire along either of the shoulder strips (lying between theshoulders X and the union Y between the, shoulder strip and the thin.side, wa-llof the tire) oralong the side walls thereof.

To adaptmy machine forthe recappingl oper;- ations, as hereinbeforedescribed, I provide the matrix section lea with*` an inwardly extendingradial. shoulder 29aand-I provideithe matrix. sectiont llibfwith aninwardly extending, radiall shoulder` 29h, the innersurface of. thematrix; sectionsV Illa. and |9b between these shoulders beingrapproximately the widthof.. only the tread or. roadcontacting portieriyof the tire so that when a. tire to.i be recapped isv placed. within themold 5; as indicated inv Fig. 4, the shoulders 29a. and 29o will extendvdown alongl and make contactwith a` substantially small area of theshoulder strip of the tire-, coniining the-new tread materialy to thetread portiony of the tireand avoiding theheating or' burning of anyappreciable amount of the old rubber of the tire. To assist inpreventing the heatirom extending to-the old rubber of the tire, Iprovidefiangesaand 30h, on. thematrixsections 19a and I9b engaging theinterior of the shellhalves 1 and 9, respectively, providing relativelylarge air spaces 3.I between the shell sec` tions and the side. wallsof` the tire.

As will'be understood by those skilled in theart, the curing of tiresrequires the inflationY ofthe tires so` as to press the new rubbermaterial snugly against the surfaces of the matrices and it is thecommon practice'. to place an inner tubel C within the tire A and tomount the tire upon either an ordinary vehicle road rim D- or specialrim, prior tothe placing of the tire in the mold 6. The upper half 9 of'the mold is then drawn downwardly toward theibasev half 'I' by means. otaplurality of. swing bolts 32, the sliding action of the hinges l0permitting this operation. The swing bolts 32- are.- preferablypivotally secured asr at` 33- to outwardly extending lugs 34. on thebase half. 'I of. themoldwhilethe opposite end of the. bolts 32 areprovided with nuts 35-which may be-A screwed down. upon outwardlyextending. ears or lugs 36. formed upon the upper. half- Si oi the mold.

After thetire-hasbeen. so placed in the moldand thef mold sectionsclamped together as shown inl Fig. 2, the inner tube C is innated toanyI desired pressure, pressing the new tread material snugly againstthe interior surface of the matrices lila and I'Sb.

Whenl the; tire is inflated, however, there is. a tendency for the sidewall portions 31 of thefcarcass of the tire to expand outwardly and toprevent undue-expansion of the side walls of the tire I prov/ideaplurality of inwardly extending radial lugs or ears 38 on each of themold halves 8 and 9, to which may be secured one or more side wallengaging rings 39 and 39', a pad of asbestos or other heat insulatingmaterial 40 being interposed between the lugs 38 and the rings 39 and 39to prevent undue transmission of heat from the shell to the side wallportions of the tire. In this manner the heat of the matrix is preventedfrom being transmitted to the old rubber of the side walls of the tire.

As will be understood by those skilled in the art, tires aremanufactured with different cross sectional diameters and in order toreadily adapt my machine for the recapping of tires of different crosssectional diameters, I provide a spacing ring |93; (see Fig. 3) whichmay be interposed b etween the meeting faces of the recapping matrixsections I9a and |9b`, the surfaces of the ring i911: having oifsetfaces conforming to the offset shape of the facesofthe matrix sections19a and I9b to prevent displacement therefrom and il' desired the ring|93: may be secured to the lower' matrix section lila as by means ofscrews 4I. Thus the spacing ring i9x provides a wider tread-engagingportion adapted to receive andy cure treads having greater tread widths.By employing spacer rings of varying thickness, the one machine may bereadily adapted to cure tires different in diameters between relativelywide limits.

However, it frequently occurs that the tread portion of the tire is sobadly worn that a portion of the breaker strip or portions of the cordor fabric structure of the tire have been worn through, in which eventto merely recap or replace the tread material at the outer periphery ofthe tire would not be sufficient and in such instances a retreadoperation is performed, this operation including the cutting away orbuffing off of the old rubber across the tread portion of the tire anddown along the shoulder strips of the tire for a short distance belowthe corner or junction formed between the tread and the shoulder stripsand new rubber material is then placed upon the carcass of the tire tobuild up both the shoulder strips of the tire and the tread.

My machine is readily adapted to cure tires in such retreading operationby the mere insertion in the machine of a pair of retreading rings orshoulder strip curing matrices 42a and 42h, the ring Ma being laid uponthe inner face ofthe mold half 1, the shape of the ring 42 including aprojecting annular ange 43a adapted to fit within the recess 3l on thematrix l9a so that the upper face 44a of the shoulder strip ring willform a continuous surface with thewsurface of the matrix 59a. Suitablegrooves 45a may be provided on the upper surface of the ring-42a toproduce any desired beading or other shoulder design. The shoulder stripring 42h is similarly placed upon the upper half 9 of the mold, theflange 43h being nested above the shoulder 29h of the matrix section19in.

With the shoulder strip rings 42a and 42h in place the tire to beretreaded, having new rubber material B thereon (see Fig. 5) beingplaced between the mold halves 'l and 9 and the mold halves beingclamped together, the inflation of the inner tube C will press newrubber material snugly against the recapping tread matrices I9a-I9b andthe shoulderstrip matrices 42a and 42h. Steam then being applied to therecapping matrices l9a and l9b will heat these shoulder strip matrices,a portion of this heat being conducted to the shoulder strip rings 42aand t2?) 75 so as to apply curing heat throughout the entire new treadmaterial. It will be noted, however, that the side wall portions of thetire A are expanded against the rings 39 and 39' which prevents undueexpansion of the side walls while at the same time avoids the conductionof heat to the old rubber of the side walls of the tire.

In either the recapping or the retreading operations, as hereinbeforedescribed, after the new rubber has been cured, the removal of the tirefrom the mold requires the lifting or swinging of the upper half 9 awayfrom the lower half l'L During the curing process there'is a tendencyfor the new rubber to stick to the matrices 19a, I9b or 42m-42h, so thatit is diicult to separate the matrices from the cured tire. I provide apneumatic opening mechanism for the mold 6 capable of supplyingsuflicient lifting power to break the matrices loose from the curedrubber. This pneumatic lifting mechanism is illustrated as comprising apair of pneumatic cylinders-50 arrangedA on opposite sides of the moldy6 and secured either to the floor on which the legs 8 rest or secured inany desired manner to the base half l of the mold. A piston (not shown)having a piston rod 5I is provided for each of the cylinders 50, theupper ends of the piston rods 5l being coupled to a cani lever 53pivoted at 54 upon the upper mold half 9, the cam surface 55 of whichbears upon a roller 5S pivoted as at 5l upon the lower mold half 7. Thuswhen compressed air or other fluid power is supplied to the cylinder 59,the lifting of the lever 53 will exert considerable lifting pressure,tending to separate the mold halves 1 and 9. If desired, a thirdcylinder 5B may be provided at the rear of the mold 6, the piston rod 59of which may press upwardly into a socket B9 formed upon a radiallyextending ear on the mold half 9. The cylinder 58 should be located moreor less centrally between the hinges I9 of the mold 5 so that byapplying power to the cylinder 58 at the same time power is supplied tothe cyli aders Eil, a three-point lifting of the mold half 9 will beaccomplished. Thus the mold half 9 may be lifted directly upwardly untilthe mat rices have been broken looseL from the cured rubber and then themold half 9 may be swung upon its hinges i9 to completely open the moldand permit removal of the cured tire. Should the tire separate from theupper matrices and not from the lower matrices, a positive separation ofthe latter may be accomplished by providing a hook-like bar 6i, one end52 of which may engage the mold section 9 while the other end 53 may beadapted to engage the rim D on which the tire is placed. Thus as themold half 9 is lifted, the hoek iii will positively draw the tire awayfrom the matrices i911 and 29a in the lower half of the mold. The rod 6|is preferably reversible, that is,

should the tire stick in the upper half of the mold. a mere reversal ofthe hook El will couple the rim D to the lower mold half 'l so that thelifting movement of the upper half 9 of the mold will positivelyseparate the tire from this half of the mold.

In order to adapt my machine for the ready curing of tires of differentdiameters, I prefer to form the upper and lower mold halves 1 and 9relatively deep in a radial direction to provide a substantially widesurface 64, against which the flanges 30a and 39h of the matrices |9aand |9b may bear. Thus by employing a series of interchangeablerecapping matrix rings l9a-I9b of different diameters, the same mold 6may be readily employed to cure the tires of large diameters as shown,in: Figs. 4 and 5:, or smaller diameters, as shown in Fig.. 3;

While Ihave shown and described the preferred embodiment of myinvention, Iv do not desire to be limited to any of; the. details, ofyconstruction shown or described herein, except asA dened in` theappended claims.

Having thus` described my invention, what I claimv andl desire: tosecure .by Letters Patent is:

1. In a vulcanizer forv selectively'retreading or recapping' tires, ashelll comprising apair of complementary annular members definingtherebetween an annulus. extending about the tread and shoulderportionsof a tire, a recappingmatrix comprising a-l pair ofcomplementary annular matri-x members whichv whenQ assembled togetherextend across the tread portion only of a tire, meanssecuring saidmatrix members respectively to said shell members,` shoulder means onsaid tinuous matrix for curing the-tread` and shoulder strip portions ofa retreaded tire.

2'. In a vulcanizing machine for selectively retreadingj or recapping;tires, a recapping matrix adapted to extend acrossand engage only the Atread portionv oi a tire-lyingbetween the shoulders of the tire to curea recapped portion only of the tire, and shoulder strip curing matricesremovably associated with said recapping matrix to form therewith asubstantially continuous matrix extending across the tread. portion anddown- Wardly over the shoulder strip portions of the tire to theVjunction of the shoulder strips with the side Walls of the tire, saidrecapping matrix being constructed and arranged to operate as a completematrix for a recapping operation.

3. In a vulcanizing machine for selectively retreading or recappingtires, a recapping matrix adapted to extend across and engage only thetread portion of a tire lying between the shoulders r of thetire to curea recapped portion only of the tire, shoulder strip matrices. adapted toextend only along the shoulder strip portions of the tire from theshoulders thereof to the junction betweenA the shoulder strip portionsand the side Walls of the tire, means removably associating saidshoulder strip matrices: with said recapping matrix to form4 therewithaV substantially continuous matrix extending over-1 both the tread andshoulder strip portions or the; tire to cure, a rte-- treaded tire, saidrecapping matrix being con.- structed and arranged to: operatev as avcomplete matrix for a recapping operation,

4. In a vulcanizing machine for selectively re-4 treading or recappingtires, a recapping matrix, adapted to extend across and engage only the`tread portion of a, tire lying between thel shoulders of the tire tocure a recapped portion only of the tire, shoulder'strp matricesadapted; toexztend only along: the shoulder stripJ portionsoi thetire-from; the shoulders thereof tothejunction between the shoulderstrip portions. and: the; side walls of the tire, means onsaidrecapping; matrix.I to removably receive and; support the shoulderstrip matrices, said shoulderl strip matrices and; said tread matrixforming. a continuous matrix extending over the tread portion andshoulder strip portions or a tire to,- cure aretreaded tire, saidrecapping matrix being constructed and arranged to operate asa completematrix for a recapping operation.

5-. In a vulcanizing machine for selectively retreading or recappingtires, a recapping matrix adapted to extend across; and engage only theftread portion of the tire lying between the shoulders of the tire tocurea recapped portion only of the tire, means associated with saidrecapping matrix for-supplying heat thereto, a pair of shoulder stripmatrices removably associated withy said recapping matrix to formrtherewith a substantially continuous matrix extending' across theY treadportion and over the should-er strip portions of the tire to cure a,retreadedl tire, said shoulder strip matrices forming metallic contactiwith said recapping matrix whereby said shoulder strip matricesl areheated solely by conduction of' heat from said recappingv matrix, saidrecapping matrix being constructed and arranged: to operate as acomplete matrix fora recapping operation.

6. In a vulcanizing machine for selectively retreading or recappingtires, a recapping matrix; adapted to extend across and engage onlyV thetready portion of thetire lying 4between the shoulders of the tire tolcure a recapped portion only of the tire, means associated with saidrecapping matrix for supplying heatY thereto, a pai-r of shoulder stripmatrices removably associated with said recapping matrix to formtherewith a substantially continuousv matrix extending across the treadportion and over the shoulder stri-p portions of1 the tireto cure. aretreaded tire, said shoulderstrip` matrices forming metallic contactwith said recapping matrix whereby saidl shoulder stripi matrices areheated by conduction of heat from said recapping matrix, said recappingmatrix being constructed and, arranged to operate. as a complete matrixforV a. recapping operation.

ARCH B. CLEVELAND.

